When server proxies run in active redirection mode,
they will expose themselves in a single Redis client protocol.
Clients don't need to support Redis Cluster Protocol.
Inside the server proxy config fileserver-proxy.toml,
set active_redirection to true,
or use environment variable UNDERMOON_ACTIVE_REDIRECTION=true.
When active redirection mode is enabled,
a server proxy will automatically redirect the requests to other server proxies.
Then if needed, other server proxies will keep redirecting the requests
until they find the owner or exceed maximum redirection limit
set by max_redirections in server proxy config file.